Tilted binary stars test theories of planet formation

Cockeyed planet nurseries may shape orbits of future solar systems

SIDE VIEW A disk of dust blocks light from one star (bottom) in HK Tauri, a binary system about 525 light-years away, in this image from the Hubble Space Telescope. New data reveal a disk, not visible in this picture, around the companion star (top).

Karl Stapelfeldt/JPL/NASA

Exoplanet orbits come in all shapes and sizes, and a pair of nearby stars is helping astronomers figure out why. Cockeyed disks of gas and dust that give rise to planets circle the two stars, new observations show. The misalignment between the two disks might nudge future planets into off-kilter orbits. Researchers hope that the discovery, the first time any one has observed disks with such different tilts, is the first step towards understanding the origin of the diverse planetary arrangements found in the galaxy.

Compared to some other planetary systems, the solar system is pretty dull. Earth and its siblings travel along nearly circular orbits in almost the same plane. A handful of planets around other stars are a bit more free-spirited. Some orbit at angles that are highly inclined relative to their star’s equator; some plunge in close to their sun before flying out to the backwaters of their system; still others carry the mass of Jupiter yet whip around their stars

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